I have an older analog PBX that I can’t replace right now. We are porting our copper POTS lines over to an AT&T SIP trunk and will be installing this gateway device do the SIP/analog translation for our PBX. I have looked and have not found how to configure my GXW4108 to make this work. I found several samples where PSTN POTS lines were being converted to SIP for use with an VOIP PBX. Does anyone know of a guide for setting this up for my situation where the SIP needs to talk analog to my PBX? Any advice is appreciated.

The diagram that you attached is exactly what I’m trying to do. I had talked with Grandstream through chat and explained the situation and they were the ones who told me I needed the GXW4108. Crumb. Looks like I need to return what I have and see if I can’t find the GXW4008. No wonder I’ve been having so much trouble getting this work. Thank you much for sharing your expertise. .